Well after most of my group were absent today, it was left up to myself and one other to defend our base. As luck would have it, it gets found and assaulted by another group. After a hard fought battle and much hilarity through voice chat during the slow, inevitable smashing through a gate, we both fell - taking four with us I might add! The base was stocked to the brim with loot, including enough car parts to get two of each vehicle going easily and enough metal to build a fortress. Thankfully we had a lot of stashes nearby that went unnoticed.
After licking our wounds, I had a suspicion as to which group it was and where the base was located (I had found a very, very large base the night before!) and we set off for revenge once the rest of our group had come online. Cut to an hour later and we have all our old loot back and then some, and our rivals will have a nice collection of land mines to negotiate in order to access and egress from their base whilst we're holed up nicely at the other end of the map.